Traditionally, innovation in mobile phones has mostly focused on the development and sales of new phone models. A new model lifetime typically lasted around two years, which also corresponds to the length of typical mobile postpaid contracts. Yet, Apple's smartphone iPhone and application store App Store have shown that the same phone model can also profit from new applications and features as well as improved performance, by updating its software. Even better, the release of a firmware or an application update can create a viral marketing buzz.